Telephone-substation circuit.



K. S. JOHNSON.

IEU-IPHONE SUBSTATION GIRGUIT. APPUCATIOI HLED $291.1. 1915;

1,263,421. Patented Apr. 23,1918.

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UNITED STATES PaTENT OFFICE.

KENNETH SIMONDS JOHNSON. OF JERSEY CITY, NEW JERSEY, ASSIGNOR, BY MESNE ASSIGNMENTS, T0 WESTERN ELEOTRIC COMPANY, INCORPORATED, A CORPORATION OF NEW YORK.

TELEPHONE-SUBSTATION CIRCUIT.

Specification of Letters Patent.

Patented Apr. 23, 1918.

1 b all whom it may concern:

Be it known that I, KENNETH Snronus JOHNSON, a citizen of the United States, residing at Jersey City, in the county of Hudson and State of New Jersey, have invented certain new and useful Improvements in Telephone-Substation Circuits, of which the following is a full, clear, concise, and exact description.

This invention relates to a suhscrihers telephone circuit of the central energy type, and has for its object to provide a circuit of this type of improved operation and efiicieucy.

In subscribers circuits of Well-known forms in which the receiver is connected with the line Wires during conversation, certain inconveniences are experienced due to the flow of direct current through the recciver.

In accordance with this invention, these inconveniences are overcome by a combination of apparatus and circuits by means of which the flow of direct current through the receiver, when it is connected with the line circuit, is prevented. This is accomplished by so connecting and combining the apparatus that the direct current potential of the receiver terminals is always the same as the potential of one of the limbs of the line circuit.

This invention may he applied to a known standard form of subscribers circuit Without the use of additional apparatus, wiring or contacts.

The regular operating features of this cir cuit will first be briefly described. Conductors 1 and 2 represent conductors forming a central energy line circuit which may be assumed as connected to a telephone system. It will be understood that proper ringing current for operating the ringer signal a may be impressed upon this line circuit at the switchboard. This ringing current path may be traced from line conductor 1, Winding 20 of the induction coil 16, conductors 3 and 10, Winding 7 of the induction coil 16, conductor 5, condenser 21, conductors 6 and 8, ringer 4:, conductor 15 to line conductor 2. Upon operating the switchhook, by lifting the telephone receiver, to include the transmitter and receiver in talking relation to the line circuit, the battery path for the transmitter may be traced as follows: from line conductor 1, winding 20 of the induction coil 16, conductors 3, 22, transmitter 19, conductor 23, contact spring 12, sivitchhook 13, conductor 14, to line conductor 2. The circuit of the telephone receiver 9 may be traced from receiver terminal 18, conductor 24, contact springs 11 and 12, conductor 23, transmitter 19, conductors 22 and 10, Winding 7 of the induction coil 16, conductor 5, condenser 21, conductors 6 and 25 to termical 17 of the telephone receiver. The order in which the contact should close or open at the svvitchhook is preferably as shown in the drawings; contact forming first between 12 and 13. contact forminglast between contacts 11 and 12. In opening, 11 and 12 disconnect first, foliovved by 12 and 13 opening.

Although the circuit for ringer 4 is completed through the serially connected Windings of the induction coil 16, the ringing efficiency is not impaired to an appreciable extent.

In describing the means by which clicks are prevented in the telephone receiver when the svvitehhook is operating, it will he noted that in the normal position. the receiver being on the sivitchhook, both terminals of the receiver are under buttery potential corresponding with the potential of line con ductor 2. This potentiai charge may be traced from line conducts conductor 15, ringer a, conductors 8 and to the receiver terminals. Now upon the receiver being lifted from the switehhook and the talking set thereby connected to the line circuit, both tei'n'iinals of the receiver retain a potential and battery polarity sign. corresponding to that of iine conductor 2. This path may be traced from line conductor conductor 1 1, sivitchhook 13, contact springs 12 and 11, conductor to receiver terminal 18, terminal 1? remaining common to line conductor 2 over the ringer path already traced. From the circuit connect-ions shown it will be seen that for either position of the svvitchhook both terminals of the receiver can only be influenced by the battery potential of line conductor 2. This exclusion of battery potential influence from line conductor 1 prevents the possibility of the receiver winding receiving an impulse of battery current. A further advantage of this circuit is the exclusion of battery current from the receiver circuit. and from the ringer circuit at all times irrespective of the position of the switchhook.

What is claimed is:

1. In a subscriber s telephone circuit, in combination a central energy line circuit, an induction coil, condenser and ringer included in serie in said line circuit, a transmitter circuit in parallel with said ringer, condenser and one winding of said induction coil, a receiver circuit in parallel with said ringer and means for closing said transmitter and receiver circuits.

2. In a subscribcrs telephone circuit, in combination a central energy line circuit, an induction coil comprising primary and secondary windings connected in series with said line circuit, a ringer and a condenser also connected in series with said induction coil and said line circuit, a transmitter, a re ceiver, and switching means for including said transmitter in bridge of said line circuit in series with one winding of said induction coil and in parallel with the other winding of said induction coil, the ringer and the condenser, and for including said receiver in parallel with said ringer.

3. In a subscribers telephone circuit, in combination a central energy line circuit, an induction coil, condenser and ringer includer in series in said line circuit, a transmitter circuit in parallel with one winding of said induction coil, the condenser and the ringer, a receiver circuit in bridge of said ringer, and switching means for closing said transmitter and receiver circuits in succession.

4. In a subscribers telephone circuit, a

pair of line conductors; a circuit connecting said line comluctors and including a transmitter and one winding of an induction coil; :1 local branch circuit in bridge of said transmitter and including another winding of said induction coil, a condenser and a signaling device; a receiver circuit in bridge of said signaling device and switching means for closing said main circuit and said receiver circuit in sequence.

5. In a subscribers telephone circuit in combination with a pair of line conductors, a main circuit including a transmitter and one winding of an induction coil; a local branch circuit including a second winding 1 of said induction coil, a condenser and a receiver in series; a signaling device connected between one terminal of said receiver and one of said line conductors, and switching means for closing said main circuit and connecting the other terminal of said receiver to said line conductor.

In witness whereof, I hereunto subscribe my name this 3rd day of September, A. D. 1915.

KENNETH SIMONDS JOHNSON.

Civics of this patent may be obtained for five cents each. by addressing the Commissioner of Patents Washington, D. C. 

